This invention relates to a bus bar arrangement for a heatable vehicle window (e.g., vehicle windshield). In particular, this invention relates to a bus bar arrangement where first and second bus bars are provided proximate opposite edges of a vehicle window, with a conductor extending from the first bus bar and leading to the opposite edge of the window so that electrical connectors for both bus bars can be provided at the same area and on the same edge of the window.
Heatable windows are known in the art. For example, see U.S. Pat. Nos. 4,668,270; 5,434,384; 4,782,216; and 4,820,902, the disclosures of which are all hereby incorporated herein by reference. See also WO 88/06095. Heatable windows conventionally include first and second conductive bus bars in electrical contact with a transparent conductive coating including an electroconductive layer. The electroconductive layer generates heat when electric current is passed therethrough. In such a manner, snow and ice may be melted from vehicle windows such as windshields, backlites, sidelites, and/or the like. Windows may also be defogged in such a manner.
In conventional heatable windows, first and second bus bars are typically located in spaced apart relation proximate opposite edges of the window. For example, see U.S. Pat. No. 4,668,270, incorporated herein by reference. This type of design often requires the electrical connector for the top bus bar to exit the window at the top edge thereof, and the electrical connector for the bottom bus bar to exit the window at the bottom edge thereof. Unfortunately, this is undesirable in that it is much more convenient if both connectors (i.e., for both bus bars) are located along the same edge/side of the window.
In an attempt to overcome the aforesaid problem, U. S. Pat. No. 4,820,902 discloses first and second conductive leads/extensions arranged from opposite sides of the top bus bar heading down the respective sides of the windshield and across the bottom side/edge of the same. In such a manner it is possible to locate the electrical connectors for both bus bars at the bottom edge/side of the windshield. Unfortunately, the design of the ""902 patent is undesirable in that it requires two separate extensions leading down both side edges of the windshield.
In a similar manner, U.S. Pat. No. 4,940,884 also requires two leads/extensions arranged from the top bus bar down to the windshield""s bottom edge. Sometimes, this double lead/extension requirement is not desirable.
It will be apparent to those skilled in the art that there exists a need for a more efficient bus bar arrangement for a vehicle windshield.
An object of this invention is to provide an efficient bus bar arrangement for a heatable vehicle window (e.g., windshield).
Another object of this invention is to provide a bus bar arrangement for a heatable vehicle window, wherein a single extension is connected to a central portion of a top bus bar and extends down one side/edge of the window to the bottom side/edge thereof so that both the top and bottom bus bar electrical connectors can be located along the same side/edge (i.e., bottom side/edge) of the window.
Another object of this invention is to fulfill one or more of the above-listed objects.
Generally speaking, an example embodiment of this invention fulfills one or more of the above-listed objects by providing a heatable vehicle windshield including a top edge, a bottom edge, and first and second side edges, the heatable vehicle windshield comprising:
first and second glass substrates laminated to one another with a polymer inclusive layer therebetween;
a coating located between said first and second substrates, said coating including at least one conductive layer;
first and second conductive bus bars in electrical communication with at least said conductive layer of said coating, so that when electric current is passed through said conductive layer via said bus bars at least a portion of the windshield is heated;
wherein said first bus bar is located in a top area of said windshield and said second bus bar is located in a bottom area of said windshield;
a conductive extension member in electrical contact or communication with a central portion of said first bus bar proximate a top central area of the windshield, said conductive extension member including: a top elongated portion extending along or adjacent the top edge windshield, and a side elongated portion in electrical communication with said top elongated portion and extending along or adjacent the side edge of the windshield and spaced from said coating; and
wherein first and second electrical connections in electrical communication with the first and second bus bars, respectively, are each attached to the windshield proximate the bottom edge thereof, at least one of said electrical connections supplying electric current to said conductive layer via an external power source.
Other example embodiments of this invention fulfill one or more of the above-listed objects by providing a heatable vehicle window comprising:
a coating supported by a first substrate, said coating including at least one conductive layer;
first and second conductive bus bars in electrical communication with at least said conductive layer of said coating, so that when electric current is passed through said conductive layer via said bus bars at least a portion of the window is heated;
wherein said first bus bar is at least partially located adjacent or along a first edge of the window, and said second bus bar is at least partially located adjacent or along a second edge of the window, said first and second edges of the window being opposite one another so that a primary viewing area of said window is positioned between said first and second bus bars;
a conductive extension member in electrical contact or communication with a central portion of said first bus bar proximate the first edge of the window, said conductive extension member extending along or adjacent said first edge of the window, and extending along a third edge of the window toward the second edge of the window so that first and second electrical connectors in electrical communication with the first and second bus bars, respectively, are each attached to the window proximate said second edge thereof; and
wherein said first electrical connector is in electrical communication with said first bus bar via said conductive extension member, and at least one of said electrical connectors supplies electric current to said conductive layer via an external power source.
This invention will now be described with respect to certain example embodiments thereof as illustrated in the following drawings, wherein: